HR: 17:00h
AN: T14B-05 INVITED     [Abstracts]
TI: Deformation of polycrystalline Ca-Perovskite up to 50 GPa
AU: * Merkel, S
EM: smerkel@issp.u-tokyo.ac.jp
AF: ISSP/Univ. of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba, 116-0014 Japan
AU: Yagi, T
EM: yagi@issp.u-tokyo.ac.jp
AF: ISSP/Univ. of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba, 116-0014 Japan
AU: Miyajima, N
EM: enkichi@issp.u-tokyo.ac.ac.jp
AF: ISSP/Univ. of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba, 116-0014 Japan
AU: Wenk, R
EM: wenk@seismo.berkeley.edu
AF: Dpt of Earth & Planet. Sc., University of California, Berkeley, CA 94720-476 United States
AU: Mao, H
EM: h.mao@gl.ciw.edu
AF: Geophysical Lab., 5251 Broad Branch Rd., N.W, Washington, DC 20015 United States
AU: Hemley, R J
EM: r.hemley@gl.ciw.edu
AF: Geophysical Lab., 5251 Broad Branch Rd., N.W, Washington, DC 20015 United States
AB: Characterizing the lattice preferred orientations and stresses that develop in deforming deep Earth phases is crucial for understanding mantle convection and its relation to seismic anisotropy. To that extend, material having the perovskite structure are particularly important with silicate and calcium perovskites accounting for about 70% and 5% of the lower mantle, respectively. In this study, we perform an ambient temperature uniaxial deformation experiment of polycrystalline Ca-perovskite up 50 GPa in the diamond anvil cell. The state of stress and lattice preferred orientations within the sample were investigated using radial x-ray diffraction techniques on BL-10 beamline in Spring8. From the variations of the d-spacings with the diffraction angle, we deduce informations on the non-hydrostatic stress in the sample. The variation of the intensities of the diffracted peaks along the Debye-Sheme rings provides information on the lattice preferred orientations within the polycrystal. Our results show that the stress in calcium silicate perovskite under non-hydrostatic compression follows a similar trend as in previous measurements on silicate perovskite. Moreover, we were able to detect evidence of lattice preferred orientations within the sample that, in combination with polycrystal plasticity modeling, allow us to deduce the active deformation mechanisms in the experiment. These results provide new constraints for modeling and understanding anisotropic properties in the deep mantle.
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 8162 Rheology--mantle
DE: 3902 Creep and deformation
DE: 3924 High-pressure behavior
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting